Environment Friendly, Efficient Chloroacetic Acid Promoted Synthesis ...

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Commun.,. 37, 1659 (2007). 10. A.M.K.A. Siddique, N.S. Jaiprakash, D.K. Nagannath, S.W. Pravin and. B.S. Devanand, Indian J. Chem. Tech., 17, 71 (2010). 11.
Asian Journal of Chemistry; Vol. 24, No. 12 (2012), 5665-5668

Environment Friendly, Efficient Chloroacetic Acid Promoted Synthesis of 1-Amidoalkyl-2-naphthols Under Neat Condition† ROBITA DUVEDI and RAJESH K. SINGH* Pharmaceutical Chemistry Division, Shivalik College of Pharmacy, Nangal-140 126, India *Corresponding author: E-mail: [email protected] AJC-11724

An environment friendly synthesis of 1-amidoalkyl-2-naphthols was developed by one-pot reaction of 2-naphthol with various aldehydes and urea or amides catalyzed by chloroacetic acid in the absence of solvent media under thermal and microwave irradiation conditions. This greener protocol offer many advantages such as shorter reaction times, simple work-up and excellent yield. Key Words: Chloroacetic acid, 1-Amidoalkyl-2-naphthol, One-pot reaction, Solvent-free media, Green chemistry.

INTRODUCTION

EXPERIMENTAL

Among the various approaches for the synthesis of organic compounds, one pot multi-component reactions appeared as a powerful tool for construction of small drug like molecules with several levels of structural diversity1,2. One of the multicomponent reactions of current interest is 1-amidoalkyl-2naphthols syntheses, which have potentially different biological activities3-5. The preparation of 1-amidoalkyl-2-naphthols can be carried out in the presence of several Lewis or Bronsted acid catalysts such as H3PMo12O40.xH2O/SiO26, montmorillonite K10 clay7, iodine8, cation-exchanged resins9, oxalic acid10, sulfamic acid11, silica sulphuric acid12, silico tungstic acid13, NaHSO4.H2O14, Fe(HSO4)315, zirconyl chloride 16, Zeolite H-Beta(IV)17 and 1,3-dibromo 5,5-dimethylhydantoin 18. However, many of the above reported protocols suffer from several drawbacks of green chemistry19 such as long reaction time, low product yield, toxicity, the use of expensive and corrosive reagents, high catalyst loading, strongly acidic and vigorous conditions. Therefore, the search for a novel green procedure and easily available catalyst with high catalytic activity promoted us to develop a safe alternate method for the synthesis of amidoalkyl naphthols. Herein, we describe practical and inexpensive methods for the synthesis of 1amidoalkyl-2-naphthol derivatives via multi-component reactions in the presence of chloroacetic acid as economical, easily available catalyst by two methods (Method A and B) (Scheme-I).

All chemicals were purchased from commercial suppliers. The melting points were determined on Veego-programmable melting point apparatus (microprocessor based) and are uncorrected. Proton (1H) nuclear magnetic resonance spectra were obtained using Brucker AC-400 F, 400 MHz spectrometer and are reported in parts per million (ppm), downfield from tetramethylsilane as internal standard. Infrared spectra were obtained with Perkin Elmer 882 spectrum and RXI, FT-IR model using potassium bromide pellets (cm-1). Elemental analyses for C, H and N were performed on Perkin-Elmer 2400 CHN elemental analyzer. Chloroacetic acid catalyzed preparation of amidoalkyl naphthols Method A-(Microwave irradiation method): To a mixture of 2-naphthol (1 mmol), aldehydes (1 mmol) and amide (1.2 mmol), effective amount of chloroacetic acid (0.2 mmol, 20 mol %) was added. The mixture was inserted in a microwave oven (LG model MS1927C) at 480 W for the appropriate time and each pulse was of 30s with intermittent time to avoid overheating. The reaction was followed by TLC. After completion of reaction, mass was cooled to 25 ºC, then the solid residue was purified by recrystallization in EtOH. Method B-(Oil bath method): To a mixture of 2-naphthol (1 mmol), aldehydes (1 mmol) and amide (1.2 mmol), effective amount of chloroacetic acid (0.2 mmol) was added. The mixture

†Presented at International Conference on Global Trends in Pure and Applied Chemical Sciences, 3-4 March, 2012; Udaipur, India

5666 Duvedi et al.

was stirred under thermal solvent-free condition at 125°C in oil bath for the appropriate time and the reaction was followed by TLC. After completion of reaction, mass was cooled to 25°C, then the solid residue was purified by recrystallization in EtOH. The spectral data of the new amidoalkyl naphthols are given below: N-[(2-Hydroxynaphthalen-1-yl)-phenyl-methyl)]urea (4a): Light brown solid. m.p. 172-173 ºC; IR (KBr, νmax, cm-1): 3319, 3067, 3025, 1694, 1594, 1336, 1076, 830, 745; 1H NMR (400 MHz,DMSO-d6): δ 8.76 (s, 1H, CONH), 7.20-7.89 (m, 11H, ArH), 6.09 (bs, 1H, -OH), 5.62(s, 2H); Anal. calcd. for C18H16N2O2: C 73.95, H 5.52, N 9.58 % ; Found: C 73.88, H 5.47, N 9.58 %. N-[(4-Chlorophenyl)-(2-hydroxynaphthalen-1-yl)methyl)]acetamide (4b): White solid m.p. 225-227 ºC; IR (KBr, νmax, cm-1): 3450, 3392, 3056, 2700, 2521, 1624, 1515, 1332, 1275, 1012, 817, 746, 555; 1H NMR (400 MHz, DMSOd6): δ 9.86 (s, 1H, CONH), 8.27 (d, =12H, 1H), 7.72(d, J = 8Hz, 1H), 7.2-7.7 (m, 10H, ArH), 3.46 (s, 1H), 2.04 (s, 3H, CH3); anal. calcd. for C19H16NO2Cl: C 70.03, H 4.95, N 4.30 %; Found: C 69.95, H 4.89, N 4.39 %. N-[(3-Nitrophenyl)-(2-hydroxynaphthalen-1-yl)methyl)]urea (4c): Light brown solid. m.p. 178-179 ºC; IR (KBr, νmax, cm-1): 3450, 3392, 3056, 1624, 1515, 1332, 1012, 817, 746; 1H NMR (400 MHz, DMSO-d6): δ 9.86 (s, 1H, CONH), 8.11-8.26 (m, 2H, ArH), 7.23-7.58 (m, 8H, ArH), 6.37 (s, 1H), 5.89 (brs, 2H); Anal. calcd. for C18H15N3O4: C 64.09, H 4.48, N 12.46; Found: C 64.16, H 4.56, N 12.38. N-[(2-Hydroxynaphthalen-1-yl)-phenyl-methyl]acetamide (4d): Light yellow solid. m.p. 241-243 ºC; IR (KBr, νmax, cm-1): 3441, 3177, 3057, 1685, 1555, 1243, 1080, 802, 770, 746; 1H NMR (400 MHz, DMSO-d6): δ 9.85 (s, 1H, CONH), 8.27 (d, J = 12, 1H) 7.9 (s, 1H), 7.75 (d, J = 8 Hz, 1H), 7.60 (d, J = 8.1 Hz, 1H), 7.30 (t, J = 8 Hz, 1H), 7.12-7.27 (m, 8H, ArH), 2.04 (s, 3H, CH3); Anal. calcd. for C19H17NO2: C 78.33, H 5.87, N 4.81 % ; Found: C 77.50, H 5.79, N 4.75 %. N-[(4-Methyphenyl)-(2-hydroxy-naphthalen-1-yl)methyl)]acetamide (4e): Light orange solid. m.p. 220-223 ºC; IR (KBr, νmax, cm-1): 3400, 3320, 3075, 3022, 1645,1592, 1512, 1435, 1320, 1280, 1114, 830, 785, 711; 1H NMR (400 MHz, DMSO-d6): δ 9.86 (s, 1H, CONH), 8.32 (d, J = 8 Hz, 1H) 7.81 (br d, 1H), 7.75 (d, J = 8 Hz, 1H), 7.61 (d, J = 8Hz, 1H), 7.33 (t, J = 8.2 Hz, 1H), 6.98-7.24 (m, 7H, ArH), 2.22 (s, 3H), 1.98 (s, 3H); Anal. calcd. for C20H19NO2: C 78.66, H 6.27, N 4.95 % ; Found: C 78.50, H 6.32, N 4.51 %. N-[(4-Dimethylaminophenyl)-(2-Hydroxynaphthalen1-yl)-methyl)]acetamide (4f). Green solid: m.p. 125-127 ºC; IR (KBr, νmax, cm-1): 3350, 3237, 3150, 1895, 1736, 1518, 1445, 1240, 1062, 741; 1H NMR (400 MHz, DMSO-d6): δ 9.68 (s, 1H, CONH), 7.9 (d, J = 8 Hz, 1H), 7.85 (d, J = 8 Hz, 1H), 7.60-7.69 (m, 5H, ArH), 7.06-7.32 (m, 4H, ArH), 6.73 (d, J = 8 Hz, 2H), 3.10 (s, 6H, CH3), 2.13 (s, 3H, CH3); Anal. calcd. for C18H22N2O2: C 72.63, H 5.56, N 8.78 % ; Found: C 72.56, H 5.47, N 8.63 %. N-[(4-Chlorophenyl)-(2-hydroxy-naphthalen-1-yl)methyl)]amide (4g): Light yellow solid. m.p. 167-168 ºC; IR (KBr, νmax, cm-1): 3450, 3350, 3320, 3075, 3022, 1694, 1592, 1512, 1322, 1222, 830; 1H NMR (400 MHz, DMSO-

Asian J. Chem.

d6): δ 9.75 (s,1H, CONH ), 7.27-7.89 (m, 10H, ArH) 6.09 (bs, 2H); Anal. calcd. for C18H15ClN2O2: C 66.16, H 4.63, N 8.57 %; Found: C 66.28, H 4.54, N 8.64 %. N-[(2-Hydroxynaphthalen-1-yl)-phenyl-methyl)]benzamide (4h): Light brown solid. m.p. 238-240 ºC; IR (KBr, νmax, cm-1): 3420, 3061, 1800, 1629, 1538, 1348, 1026, 822, 750; 1H NMR (400 MHz, DMSO-d6): δ 10.09 (bs, 1H, CONH), 8.91 (bs, 1H), 7.40-7.91 (m, 16H, ArH); Anal. calcd. for C24H19NO2: C 73.95, H 5.52, N 9.58 % ; Found: C 73.88, H 5.47, N 9.63 %. N-[(4-Methyphenyl)-(2-hydroxy-naphthalen-1-yl)methyl)]benzamide (4i): Light orange solid. m.p. 216-217 ºC; IR (KBr, νmax, cm-1): 3320, 3260, 3052,1980, 1694, 1570, 1450, 1350, 1210, 790; 1H NMR (400 MHz, DMSO-d6): δ 10.2 (s, 1H, CONH), 8.95 (d, J = 8 Hz,1H), 8.80 (d, J = 8.1 Hz, 1H), 7.81-7.84 (m, 4H, ArH), 7.77 (d, J = 8.2 Hz, 1H), 7.72 (d, J = 8.3 Hz, 1H), 7.16-7.51 (m, 9H, ArH), 7.02(d, J = 8 Hz, 2H), 2.23 (s, 3H) ; Anal. calcd. for C25H21NO2: C 81.72, H 5.76, N 3.81 % ; Found: C 81.63, H 5.68, N 3.88 %. N-[(4-Chlorophenyl)-(2-hydroxy-naphthalen-1-yl)methyl)]benzamide (4j): Light yellow solid. m.p.188-189 ºC; IR (KBr, νmax, cm-1): 3419, 3179, 1629, 1513, 1339, 1012, 811, 723, 1H NMR (400 MHz, DMSO-d6): δ 10.14 (s, 1H, CONH), 8.90 (d, J = 8 Hz, 1H), 8.12 (d, J = 8 Hz, 1H), 7.81 (d, J = 8 Hz, 2H), 7.78 (d, J = 8 Hz, 1H), 7.73 (d, J = 12 Hz, 1H), 7.20-7.52 (m, 11H, ArH); Anal. calcd. for C24H18NO2Cl: C 74.32, H 4.68, N 3.61 % ; Found: C 73.80, H 4.76, N 3.55 %. N-[(4-Methyphenyl)-(2-hydroxy-naphthalen-1-yl)methyl)]urea (4k): Light orange solid. m.p. 117-119 ºC; IR (KBr, νmax, cm-1): 3350, 3240, 3075, 3022, 2804, 1694, 1592,1944, 1222, 1140, 930, 840, 713; 1H NMR (400 MHz, DMSO-d6): δ 9.51 (s, 1H, CONH), 8.72 (d, J = 4 Hz, 1H), 8.12 (s, 2H), 7.18-7.50 (m, 12H, ArH), 2.25 (s, 3H); Anal. calcd. for C19H18N2O2: C 74.49, H 5.92, N 9.14 % ; Found: C 74.38, H 5.96, N 9.21 %. N-[(2,5-Dimethoxyphenyl)-(2-hydroxynaphthalen-1yl)-methyl)]acetamide (4l): White solid. m.p. 250-252 ºC; IR (KBr, νmax, cm-1): 3392, 3156, 3000, 2930, 1624, 1545, 1430, 1375, 1250, 1080, 817, 790; 1H NMR (400 MHz, DMSO-d6): δ 9.72 (s, 1H, CONH), 8.45 (d, J = 8 Hz, 1H), 7.71-7.81 (m, 2H), 7.70-6.90 (m, 9H, ArH), 3.60 (s, 3H, OCH3), 3.45 (s, 3H, OCH3), 2.02(s, 3H, CH3); Anal. calcd. for C21H21NO4: C 71.78, H 6.02, N 3.99 % ; Found: C 71.50, H 6.50, N 3.90 %.

RESULTS AND DISCUSSION In order to optimize the reaction conditions, we carry out the synthesis of N-[phenyl-(2-hydroxynapthalene-1-yl)methyl] acetamide as a model reaction (Scheme-I). We studied the reaction by using 2-naphthol, benzaldehyde and acetamide in the ratio (1:1:1.2 mmol) with different quantities of chloroacetic acid as catalyst under solvent free conditions (Fig. 1). It was found that the best result was obtained when the reaction was carried in the presence of 0.2 mmol (20 mol %) chloroacetic acid. The fewer amounts gave a low yield and the more amounts could not cause the obvious increase for the yield of product. After optimization of the reaction conditions, we studied the generality of this method. Using this procedure, different kinds of aromatic aldehydes (1 mmol) and urea (1.2 mmol) or

Vol. 24, No. 12 (2012)

Synthesis of 1-Amidoalkyl-2-naphthols Under Neat Condition 5667

O +

R

OH H2N

CHO

OH

Chloroacetic acid (catalyst)

+

R1

Method(A and B)

NH R

(1)

O R1

(3)

(2)

(4)

Scheme-I: Method A: Microwave irradiation; Method B: Oil bath TABLE-1 CHLOROACETIC ACID CATALYZED ONE-POT SYNTHESIS OF 1-AMIDOALKYL-2-NAPHTHOLS* Entry

Aldehyde (R)

Amide (R1)

Product

Method A Method B m.p. (ºC) Time (min)/Yield (%)** Time (min)/Yield (%)** (lit. m.p)ref 1. H NH2 4a 7/86 15/82 172-173 (175-176)15 2. 4-Cl CH3 4b 11/88 25/87 225-227 (224-227)15 3. 3-NO2 NH2 4c 7/87 25/82 178-179 (178-180)15 4. H CH3 4d 6/85 15/92 241-243 (239-240)10 5. 4-CH3 CH3 4e 5/86 14/82 220-223 (222-223)19 6. 4-N(CH3)2 CH3 4f 13/80 35/78 125-127 (123-125)19 7. 4-Cl NH2 4g 9/83 16/79 167-168 (169-170)15 8. H C6H5 4h 9/83 18/80 238-240 (237-239)10 9. 4-CH3 C6H5 4i 6/86 14/82 216-217 (215-216)15 10. 4-Cl C6H5 4j 11/84 17/77 188-189 (187-189)15 11. 4-CH3 NH2 4k 10/88 15/84 117-119 (118-120)15 12. 2,5-(OCH3)2 CH3 4l 12/83 20/80 250-252 (251-253)19 *Yields refer to pure products were characterized by comparison of their physical and spectral data with that of authentic samples. **All the compounds are known, structure of the products were confirmed from their spectral IR, 1H NMR and CHN data; Method A: Microwave irradiation; Method B: Oil bath.

Yield (%)

100

Method A

80

Method B

R

60

R1CONH2

CHO O

OH

OH H

H H

40

R

NHCOR1 R

O-QMs

20 0

Scheme-II: Mechanism of choloroacetic acid catalyzed reaction

5

10

20

30

Catayst amount (mol%) Fig. 1. Amount of the catalyst optimization for the synthesis of 1amidoalkyl-2-naphthols

amide were treated with 2-naphthol to produce a range of amidoalkyl naphthols (Table-1). In all cases, aromatic aldehydes with substituents carrying either electron-donating or electron-withdrawing groups reacted successfully and gave the products in high yields. It was observed that the microwave method was found to have beneficial and superior effect on the reaction as compared to the oil bath method. The proposed mechanism for the chloroacetic acid catalyzed preparation of amidoalkyl naphthols is shown in Scheme-II. The condensation of 2-naphthol with aromatic aldehyde under acid catalyst gave ortho-quinone methides. The generated ortho-quinone methides reacted with amide via the conjugated addition to afford 1-amidoalkyl-2-naphthols. Electron-withdrawing groups on the benzaldehydes in the ortho-quinone methides increase the rate of the 1,4-nucleophilic addition reaction because the alkene LUMO is at lower energy in the presence of electron-withdrawing groups as compared to electron donating groups.

To show the merit of the present work in comparison with reported results in the literature for the synthesis of amidoalkyl naphthols, we have tabulated turn-over frequency {TOF = yield (%)/[reaction time (min) × mol % of catalyst]} of these catalysts. As Table-2 indicates, chloroacetic acid is superior to the previously reported catalysts in term of TOF. Conclusion Microwave assisted synthesis of amidoalkyl naphthols using chloroacetic acid is superior and fast over the oil bath method. The advantages of presented green protocol are shorter reaction time, clean reaction profile, simple work up, reliable, environmentally benign, safe, non-toxic and moreover, under solvent-free conditions. Thus, we have elaborated a novel, highly efficient and green approach for the synthesis of amidoalkyl naphthols.

ACKNOWLEDGEMENTS The authors are thankful to Dr. D.N. Prasad, Principal, Shivalik College of Pharmacy, Nangal for providing the laboratory facilities. Thanks are also due to SAIF, Panjab University, Chandigarh for spectral analysis.

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Asian J. Chem. TABLE-2 COMPARISON OF THE TOF RESULTS OF CHLOROACETIC ACID WITH THOSE OBTAINED BY THE RECENTLY REPORTED CATALYSTS

Catalyst (d) Catalyst, (mol %) Time (min) Yield (%) TOF (c), (min-1) Ref. Chloroacetic acid 20 (a) 6; (b) 15 85; 92 0.7083; 0.3066 Present work H3PMo12O40.xH2O/SiO2 3.17 15 91 1.91 10 MontmorilloniteK10 Clay 0.1 g 90 89 0.00033 11 KHSO4 15 60 90 0.1 12 Iodine 5 330 85 0.051 13 Sulfamic acid 51.5 15 89 0.115 16 Fe(HSO4)3 5 65 83 0.255 20 Cyanuric chloride 10 10 91 0.91 21 (a) Method A (b) Method B. (c) Turn-over frequency (d) Reaction condition: 2-naphthol:benzaldehyde: acetamide in the ratio (1:1:1.2 mmol)

REFERENCES 1.

2. 3. 4. 5. 6. 7. 8.

(a) A. Domling and I. Ugi, Angew. Chem. Int., 39, 3168 (2000); (b) N.K. Terret, M. Gardner, D.W. Gordon, R.J. Kobylecki and J. Steele, Tetrahedron Lett., 51, 8135 (1995). A. Corma and A. Garcia, Chem. Rev., 103, 4307 (2003). A. Domling, Chem. Rev., 106, 17 (2006). (a) I. Szatmari and F. Fülop, Curr. Org. Synth., 1, 155 (2004); (b) A.Y. Shen, C.T. Tsai and C.L. Chen, Eur. J. Med. Chem., 34, 877 (1999). M. Damodiran, N.P. Selvam and P.T. Perumal, Tetrahedron Lett., 50, 5474 (2009). A. Zare, A. Hasaninejad, E. Rostami, A. Reza, M. Zare and F. Khedri, E-J. Chem., 7, 1162 (2010). S. Kantevari, V.N. Vuppalapati and L. Nagarapu, Catal. Commun., 8, 1857 (2007). B. Das, K. Laxminarayana, B. Ravikanth and B.R. Rao, J. Mol. Catal. A: Chem., 261, 180 (2007).

9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19.

S.B. Patil, P.R. Singh, M.P. Surpur and S.D. Samant, Synth. Commun., 37, 1659 (2007). A.M.K.A. Siddique, N.S. Jaiprakash, D.K. Nagannath, S.W. Pravin and B.S. Devanand, Indian J. Chem. Tech., 17, 71 (2010). R.R. Nagawade and D.B. Shinde, Chin. J. Chem., 25, 1710 (2007). G. Srihari, M. Nagaraju and M.M. Murthy, Helv. Chim. Acta, 90, 1497 (2007). A.R. Supale and G.S. Gokavi, J. Chem. Sci., 122, 189 (2010). H.R. Shaterian and H. Yarahmadi, ARKIVOC, 105 (2008). H.R. Shaterian, H. Yarahmadi and M. Ghashang, Bioorg. Med. Chem. Lett., 18, 788 (2008). R.N. Nagawade and B.S. Shinde, Acta Chim. Slov., 54, 642 (2007). S.R. Mistry, R.S. Joshi and K.C. Maheria, J. Chem. Sci., 123, 427 (2011). S. Habibzadeh and H.G. Bosra, J. Chin. Chem. Soc., 58, 6 (2011). P.T. Anastas, Green Chemistry Theory and Practice, Oxford University Press, New York (2000).